The tropical Atlantic has been putting on quite the show over the last couple of weeks of Hurricane Harvey (Category 4). . .I’m sure you heard of that one, followed by Irma (Category 5), Jose (Category 4), and Katia (Category 2). Katia made landfall last night in Mexico and now we continue our focus on Irma and Jose. Why is it so active? A few reasons: warm ocean (sea surface temperature and high ocean heat content), lack of a true El Nino Southern Oscillation (ENSO) signal, though it looks like a weak La Nina, little to no shear throughout much of the basin, a lack of dust from the Sahara, and a strong Azores high. Oh yeah, on top of that, we have the Madden-Julian Oscillation (MJO) more or less stuck in favorable phases for the Atlantic (8, 1, 2, 3) and forecasts suggest that stays in place for a while.

ECMWF MJO verification and forecast courtesy of the Climate Prediction Center (CPC). Click here to open in a new window.

GEFS MJO verification and forecast courtesy of CPC. Click here to open in a new window.

One product I noticed in use at the Ocean Prediction Center (OPC) on Friday, 09/08/17 was the GOES-16 Daytime Convection RGB, so I thought this would be a nice opportunity to show you all three current Atlantic systems with a comparison to the 10.3 µm “clean” channel.

GOES-16 Daytime Convection RGB of Hurricane Irma valid 1100 UTC to 2300 UTC on 09/08/17. *Preliminary, Non-Operational Data* Click here to open in a new window.

Note the bright yellow coloring that highlights, new convection with smaller ice particles indicating strong overshooting tops in the outer rainbands, while the main central dense overcast (CDO) surrounding the eye also gets brighter. This indicates that after the eyewall replacement cycle ended, the new eyewall started to contract and strengthen (winds at this time were 155 mph, but shortly after this strengthened to 160 mph.

GOES-16 10.3 um “clean” infrared window channel similar to the previous animation of Hurricane Irma. *Preliminary, Non-Operational Data* Click here to open in a new window.

Notice that the 10.3 µm “clean” window shows us the brightness temperature of the coldest cloud tops. Although you can see the new overshooting tops, as those thunderstorms rotate around the CDO, it gets more difficult to identify the newer, important convection.

GOES-16 Daytime Convection RGB for Hurricane Jose valid 1000 UTC to 2045 UTC on 09/08/17. *Preliminary, Non-Operational Data* Click here to open in a new window.

By contrast, notice how compact Hurricane Jose became as it strengthened to a 150 mph Category 4 hurricane on Friday (09/08/17). Again, the beginning of the animation shows plenty of yellows that indicate new convection, wile the older convection fades to oranges, then reds. Also notice how the CDO becomes more yellow as the eye becomes cleaner and the storm takes on a more donut structure, even with the strong outflow channel to the northeast that makes the storm look lopsided. Could this RGB be helpful in identifying CDO changes? Or help with indicating eyewall replacement cycles (ERCs) in conjunction with microwave imagery?

GOES-16 10.3 um “clean” infrared imagery similar to the previous animation of Hurricane Jose. *Preliminary, Non-Operational Data* Click here to open in a new window.

Again, to contrast the Daytime Convection RGB, the above 10.3 µm animation shows very cold cloud tops, but the newer convection starts to blend in with the CDO over time. Do you see other differences?

GOES-16 Daytime Convection RGB of Hurricane Katia valid 1200 UTC to 2357 UTC on 09/08/17. *Preliminary, Non-Operational Data* Click here to open in a new window.

Finally, Hurricane Katia was very small in comparison with the other two hurricanes, but notice there are differences in the intensity of the convection on Friday (09/08/17). What do you see in the imagery? There are less yellows than in Irma or Jose, yet the storm intensified to a Category 2, 90 kt (105 mph) hurricane prior to landfall on Friday evening. The warming clouds and less cold, newer convection may have been due to dry air entrainment due to the close proximity to mountainous land nearby and a weak trough to the north.

GOES-16 10.3 um “clean” infrared imagery similar to the previous animation of Hurricane Katia. *Preliminary, Non-Operational Data* Click here to open in a new window.

How does the 10.3 µm imagery above contrast with the Daytime Convection RGB?

So, what is steering Irma? What about Jose and Katia? Well, I’m glad you asked. . .

GOES-16 Air Mass RGB image valid at 0900 UTC 09/09/17. *Preliminary, Non-Operational Data* Click here to open in a new window.

The GOES-16 Air Mass RGB image (courtesy of NASA SPoRT) above with my crude drawings show a rough idea of the players affecting the steering flow around the three hurricanes. Katia has made landfall as it was pushed southwest due to the old cold frontal boundary (responsible for the cool air in most of the country) along with a disturbance highlighted in the yellow circle. This disturbance will close off over the Tennessee Valley area and help to pull Hurricane Irma north, then northwestward in the next 48 hours. Finally, Jose (east of the Lesser Antilles) will be pulled north through a weakness in the ridge due a weakness created by the Tropical Upper Tropospheric Trough (TUTT in the yellow “T”) to the northeast and Irma’s broad circulation. Since the current trough over the northeast U.S. moves east/northeast and the central Atlantic TUTT remains stationary, Irma gets left behind in the southeast U.S., but weakening after landfall, while Jose gets left behind and may perform a tight anticyclonic loop before “possibly” moving northwest. We’ll deal with Jose later. . .

I have included the GOES-16 Air Mass RGB and 7.3 µm low-level water vapor animations below so you can get a better feel of the overall pattern.

Following on the heels of our post on the early March 2017 eruption of Bogoslof in the Aleutian Islands, the Washington Volcanic Ash Advisory Center (VAAC) located at the NESDIS Satellite Analysis Branch (SAB) noted an interesting SO2 signal following the eruption of Kambalny on the Kamchatka Peninsula in the various Himawari multispectral imagery. The ash plume lasted many hours and was carried hundreds of miles from the Kamchatka Peninsula.

From SAB Analyst, Mike Turk (10pm March 25 – 7am March 26): I had to handle the coordination with Tokyo and Anchorage VAACs regarding possible hand off of responsibility from Tokyo to Washington. Anchorage-VAAC called to discuss need for a Significant Meteorological Information (SIGMET) statement for the Oakland Flight Information Region (FIR). the Nighttime Microphysics RGB clearly showed the initial penetration of ash into the Oakland FIR .

Himawari-8 Air Mass RGB with the ash cloud (white) and SO2 plume (light pink) faintly visible near the southern tip of the Kamchatka Peninsula as they get caught up in the dry, stratospheric air (red shading), valid 03/25/17 – 03/27/17. Click here to enlarge

From SAB Analyst, Ellen Ramirez (10pm March 26th -8am March 27th): At the beginning of my shift it was daylight over Kambalny and I could not discern the ash plume in the Daytime Microphysics RGB. Several hours later after sunset the plume was most distinguishable in Nighttime Microphysics RGB, followed by the Dust RGB, and barely in the Air Mass RGB but only because I knew where to look.

The ash plume is enhanced in the multispectral imagery due to the 12.4 µm – 10.4 µm band difference. The SO2 plumes are enhanced in the multispectral imagery due to the absorption of SO2 at the 8.6 µm (Dust) and 7.3 µm (Air Mass) wavelengths.

For more satellite analysis of this eruption, please see the CIMSS Volcano Blog entry on Kambalny.

All multispectral imagery in this post is courtesy of NASA SPoRT through the GOES-R Proving Ground.

Today GOES-16 data started flowing over the AWIPS Satellite Broadcast Network (SBN/NOAAPort) data feed. SPoRT is able to ingest this data into a test AWIPS system to view an analyze the imagery. Over the past several years, SPoRT has had an active role in transitioning proxy GOES-R multispectral (i.e. RGB) imagery derived from polar-orbiting sensors to prepare NWS offices and National Centers for advanced capabilities available with GOES-16. Below is animation of the Air Mass RGB in which forecasters can use to analyze temperature and moisture characteristics surrounding synoptic scale systems and stratospheric air intrusions to anticipate rapid cyclogenesis. Although this RGB is not available to NWS forecasters today, SPoRT is working with the Total Operational Weather Readiness – Satellites (TOWR-S) team to transition the capability to derive client side RGBs in AWIPS-II to NWS offices.

So, it’s no secret. . .Hurricane Patricia is mean and is disrespecting the records and will soon visit Mexico in a most unwelcome way. With a current intensity of 175 kts (200 mph) and a central pressure that is a mindboggling 879 mb, this hurricane has joined the elite list of “most powerful storms ever recorded on Earth!” I would like to give you some satellite perspective of this incredible storm and I will let the animations do most of the talking.

The GOES-13 Infrared animation above with the GLD-360 Lightning Density product (produced at OPC) shows the intense bursts of lightning around the eyewall during the rapid intensification stage overnight and continuing into this afternoon. Typically this indicates weakening, but due to the relative lack of lightning in the outer bands (away form the northern band near the Mexico coast), I would hypothesize it’s more due to the intense thunderstorms activity in the eyewall with cloud-top temperatures near -90C.

Not to be completely outdone, a massive extratropical storm is strengthening in the South Atlantic Ocean north of Antarctica which the GFS initialized at 934 mb!

This is truly an incredible day and I didn’t even touch on the recurvature of Typhoon Champi, the heavy rains occurring and expanding from Texas into Louisiana, as well as the 3 hurricane-force storms that the Ocean Prediction Center is anticipating over the next couple of days in the North Pacific and North Atlantic!!!! These are busy days and I’ll try to post more to keep everyone updated with more satellite fun!

Conventional satellite imagery depicted an upper low digging slowly southeast into the Central Rockies. Meanwhile, an active subtropical jet was focused farther south underneath it lifting northeast across northern Mexico and downstream across the wind across the Gulf Coast states.

While there was broad warm air advection, instability and a very moist airmass focused across the western Gulf Coast region, there were no identifiable features on the larger scale in conventional satellite imagery that suggested a forcing mechanism for organized convection to initiate. However, upon closer inspection of morning GOES-RGB airmass imagery, a subtle and small scale, but identifiable feature appeared that reflected a shortwave impulse. This impulse was tracked crossing the Rio Grande river at 12Z/16, and in conjunction with deep moisture and diurnal instability proved to be the catalyst for increasingly organized convection after 18Z/16 that continued past 00Z/17 along the Upper Texas coast and coastal areas of southern Louisiana. The result was 4 to 8 inches of rain, and flash flooding in the suburbs of Houston, TX.

While most of us thaw out after a rough February into the first week of March, winter weather-wise, the Southern Hemisphere is boiling with deep convection that has spawned three tropical cyclones near Australia and the South Pacific, one tropical cyclone in the West Pacific (a twin of sorts to TC Pam in the South Pacific), and an invest area near the coast of southern Brazil. There is a weak El Nino that is centered near the dateline in the West Pacific and there is currently a strong westerly wind burst associated with the current state (Phase 6 moving to 7) of the Madden-Julian Oscillation (MJO). TC Pam and TS Bavi look to have formed near this burst as part of the overall monsoon trough that straddled the equator. TC Nathan may have also formed due to the strength of the monsoon trough, while TC Olwyn formed well to the west on the other side of Australia.

I have put together some animations and a snapshot of the of the four storms near Australia and Guam.

MTSAT-2 Infrared satellite image of four concurrent tropical cyclones in the western Pacific and eastern Indian Oceans valid at 2032 UTC on 03/11/2015.

A four day animation that shows the development of TC Pam, TC Nathan, TC Olwyn, and TS Bavi valid from 03/08/15 to 03/11/15.

MTSAT-2 Infrared Satellite imagery with GLD-360 lightning strikes overlaid showing the lightning distribution (cloud-to-ground and some intra-cloud) associated with all four tropical cyclones valid from 1432 UTC on 03/10/2015 to 2032 UTC on 03/11/2015.

Finally, a new invest area has been identified near the southern coast of Brazil on the tail end of a mid-latitude storm system. This is rare, but not unprecedented as this area occasionally sees subtropical development during the Southern Hemisphere summer. The RGB Air Mass animation below shows the system still developing, but appears to be embedded in a cold core system as indicated by the orange, red, and purplish coloring. There is a significant amount of upper-level dry air that the system has to fight through, but water temperatures are slightly above normal (+0.5C), so some additional development is possible (thank you to Dr. Jeff Masters for the information).

SEVIRI RGB Air Mass animation of Invest 90Q in the South Atlantic valid on 03/11/2015.

Thanks for reading! I’ll try to follow up on these systems as they develop.

So, we have all probably noticed that it has been cold lately. Well, due to the ample snow cover over much of the U.S. at this time, the baroclinic zone is sharpening over the lower Mississippi and Ohio River Valleys this afternoon with the aid of shortwave energy coming out of a cutoff low located over the Southwest U.S. One of the Ocean Prediction Center forecasters, Tim Collins, noted the strong contrast in temperature on either side of this zone in the RGB Air Mass image from MODIS below.

MODIS RGB Air Mass image of the strong baroclinic zone valid on 03/04/15.

Note the orange and purplish coloring to the north (above) of the moisture plume (cirrus, etc). This delineates the colder, drier air advancing south and east, while to the south (below) of the clouds there is a greenish coloring that denotes warmer mid-tropospheric air associated with a ridge of high pressure aloft over the Gulf of Mexico and Southwest Atlantic.

MODIS Water Vapor image to compliment the RGB Air Mass image valid on 03/04/15.

For contrast, the above image is the ~6.7 um water vapor channel from MODIS. Notice that north of the moisture plume you can see evidence of the lower tropopause and cold air by the relative smoothing noted in the image (lighter blue coloring due to the enhancement). To the south of the moisture plume, you can see the dry air at ~400-500 mb associated with the ridge over the Gulf of Mexico.

This baroclinic zone will continue to sharpen overnight and produce a significant snowstorm for many in the central and eastern US into tomorrow.